FIELD OF THE INVENTION
This invention relates to apparatus for improving visual resolution in the cockpit of an aircraft at night and more particularly, to a fiber optic finger light which includes at least one light-emitting diode capable of emitting light of selected color, and most preferably, green and red light-emitting diodes (LED) mounted in a housing adapted for strapping to one hand and operated by a 3-position switch. A lens is mounted forwardly of each of the light-emitting diodes and focuses light from a selected one of the light-emitting diodes on one end of one of a pair of light-transmitting fibers, which fibers extend through the housing in a pair of fiber optic simplex cables which join at a flexible duplex fiber optic cable mounted on the housing. When the duplex fiber optic cable is strapped to a finger and the housing strapped to the wrist, red or green light is selectively emitted from the opposite end of the corresponding optic fiber by manipulation of the switch for focussing on charts, instruments, check lists and the like, in the aircraft.
On today's modern battlefield, many wars are being fought at night. The United States military has been preparing for such night action by using night vision devices such as second generation PVS-5 and third generation ANVIS-6 night vision goggles. Imaging systems have been used extensively in Marine Aviation since 1986 and since that time, the introduction of the ANVIS-6 night vision goggles has greatly enhanced the capability and survivability of both crews and aircraft. The military is moving toward complete integration of ANVIS equipment over the older PVS system, since the former represents the current state of the art in night vision imaging. Development of the ANVIS-6 has doubled the goggle reliability to a system life span of over 7500 hours. In addition to this significant life span extension, the system was designed from the outset for aviators, rather than slow moving ground vehicles, for which the earlier PVS-5 system was developed. The third generation goggles facilitate in-flight adjustment by means of knobs that move the goggles fore and aft, up and down and allow eye span and focal adjustment. These improvements allow the pilot the option and accessibility to make fine adjustments in flight, which option was not available in the older PVS-5 system.
Night vision goggles facilitate significant enhancement of visual references over the unaided eye. However, among the several problems associated with these night vision goggle apparatus are:
1. A limited field of view from the normal horizontal field of view of 200 degrees to only 40 degrees, when all the proper adjustments are made to the equipment.
2. The goggles allow the user to see the size of visualized objects but does not facilitate depth perception.
3. There is a difference in visual acuity or the ability to resolve detail. All Naval Aviators are required to possess 20/20 visual acuity unless a waiver is obtained to enter flight school. In order to conduct Carrier Qualifications (shipboard landings) the minimum visual acuity a pilot may possess is 20/50, corrected to 20/20 with the use of glasses. However, shipboard operations are continuously being conducted by pilots flying on PVS-5 systems at 20/50 (optimum conditions) and 20/40 on the ANVIS-6 apparatus. When operated under starlight conditions, the visual acuity drops to 20/80 on ANVIS-6 and 20/100 while using PVS-5's.
Supplemental cockpit lighting is extremely important in night flying, since the pilot must integrate visual cues supplied by the goggles and combine this with information gained by the flight instruments. This is very critical in many aerial operations, for example, while flying close to the ground in helicopters during missions.
Marine aircraft are equipped with a "quick fix" interim, which consists of a blue light kit that can be quickly installed while the aircraft is on the ground. The kit contains various sized lenses to fit over peanut lights, map lights, secondary console lights and other light emitting sources. These blue lenses filter out the light which degrade the capability of the goggles.
Red, white and yellow light shut down the Anvis-6 system. Red is the color of standard night instrumentation lighting and a filter to shut out wave lengths in the blue-green spectrum has been installed in the ANVIS-6 system and this expedient facilitates the use of blue lenses.
Although not located on the individual instruments, secondary lighting is located in the cockpit of an aircraft to illuminate the primary flight and engine instruments. A primary problem associated with the location of secondary lights lies in the fact that the intensity required to illuminate the instruments located farthest from the light source causes windshield glare and, in turn, degradated performance of the goggles, especially during low ambient light, such as starlight.
The cost involved in changing the individual instrument lighting system in aircraft is enormous, and two alternatives are possible:
1. Remove all light-emitting bulbs in the aircraft cockpit and replace them with blue-green bulbs that have either a blue or green coating or tinted glass that operate within the parameters of the night vision devices; or
2. Incorporate an auxiliary light that is compact, portable and reliable and can be used in the goggle environment and on regular night missions. I therefore describe herein a light-weight, reliable finger light that incorporates a blue or green light with a red light, using fiber optics.